short in wiper switch

No11 fuse blows when I switch the ignition on. I have checked the wiring to the wiper switch and motor with no problems found

The short seem to be in the wiper switch. If I don't put the three bolts in which clamp the switches to the steering column there is no short between the fuse and earth. As well as clamping the switches to the column the bolts effectively earth the metal plate on top of the switch pack. Therefore  I think the problem is that part of the wiper switch is contacting the earthed metal clamping plate.

Could anyone tell me if this is likely to be the problem and if so, can I fix it without buying a new switch. Perhaps there should be either insulating washers or an insulating gasket between the bolts and the metal top plate which is missing?

The switch is a short between Earth and the Wiper relay to operate the motor.

Those 3 bolts don't have insulated washers on them.
The Wiper is controlled by F11.



here are the wiper switch tests from the Bentley.



If the Switch is mal-adjusted then the wiper can be on all the time,

The switch acts as a short to ground and it is intermittent usually depending on if you are using the wipers.

I would suspect the Motor, Wiper and or Washer, or the Relay over the switch.

Do the Switch tests first as outlined in the Bentley, then Remove the Connection on Both motors, then the Relay.

Troubleshoot the Motors first by unplugging it, as to blow a fuse that size, the motor or the Relay has to have a direct path to ground.
The switch is used to turn things on by apply a ground path for them to operate through the item in question.
You didn't say that the Wiper motor engaged a wee bit or that the washer motor tried to run.







 

I also forgot to state that you also may need to check the wiring for chafing and a direct short to ground.